An organism’s motility refers to its capacity for self-propelled movement while utilising metabolic energy. Here, let us have a look at both motile and non-motile bacteria with examples.
Table of Contents
- Motile and Non-motile Bacteria
- Hanging Drop Preparation
- Motility Test Medium
- Frequently Asked Questions
Motile and Non-motile Bacteria
Non-motile bacteria are types of bacteria that don’t have the capabilities or physical makeup to move through their environment on their own. Non-motile bacteria only develop along the stab line when they are cultivated in stab tubes. This line will appear diffuse and spread into the media if the bacteria are mobile. The cilia and flagella of the cell are the components that enable movement or motility. The majority of the motility mechanisms that developed in bacteria also did so in archaea. Also the pathogenicity of many bacteria, especially those that infect mucosal surfaces, depends on motility.
Motile Bacteria Examples
- Escherichia coli
- Helicobacter pylori
- Pseudomonas aeruginosa
Non-motile Bacteria Examples
- Yersinia pestis
- Klebsiella pneumoniae
- Staphylococcus aureus
Hanging Drop Preparation
The laboratory method used in the observation of living microorganisms (viable microorganisms), particularly bacteria, without staining them and to see their motion due to flagella, is known as hanging drop preparation. Thus, it distinguishes motile bacteria from non-motile bacteria.
A drop of a broth culture of a bacterial suspension to be analysed is placed on a glass coverslip and covered with a stick substance, preferably petroleum jelly. This coverslip containing the bacterial specimen is then quickly inverted over a glass slide known as a cavity slide or depression slide that contains a depression or cavity, allowing the drop to hang freely. The motility of the organism is next checked by microscopically examining the hanging drop preparation, ideally in low light to improve visibility and contrast.
Also Check: Shapes of Bacteria
Motility Test Medium
Most frequently, a semi-solid agar medium is used to illustrate bacterial motility. Motile bacteria swarm and diffuse on semi-solid agar media that is visible to the naked eye. SIM medium (Sulphide Indole Motility medium), a combined differential medium that examines three different parameters namely sulphur reduction, indole production and motility is the primary medium used for this purpose. These media are extremely soft which makes it easy for germs to move through them and cause cloudiness.
Agar is poked in the centre with the bacterial inoculum. A widespread zone of growth extending from the line of injection indicates bacterial movement. While some organisms spread out into the entire medium, others appear as nodules or tiny regions that extend from the inoculation line. The non-motile bacteria grow only in the area where they are infected in the soft agar tube.
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